As the ball comes, the player immediately turns her shoulders and takes her racket back. In this case she opts to let the ball drop after it has bounced, which means she has to move backwards. You can also see that she shifts her weight from the back to the front foot, in what is called a 'closed' hitting stance, where her right foot steps closer to the sideline than her left. You can also use a 'square' - or 'neutral' - hitting stance, where the last step before hitting the ball is taken forward, in the direction of the net. While taking this last step forward, she drops her racket at the end of the backswing. This is the start of the forward and upward swing. The contact point is around hip height. At impact, the hips and shoulders stay completely turned. As you can see, the racket swings forward and up, while the left arm swings back for balance, and to help maintain a turned position. © http://www.tennis-for-beginners.com